1. Field of the Invention
The present invention relates to a novel azo pigment, an electrophotographic photosensitive member comprising the azo pigment, and a process cartridge and an electrophotographic apparatus that comprise the electrophotographic photosensitive member.
2. Description of the Related Art
As electrophotographic photosensitive members, electrophotographic photosensitive members (organic photosensitive members) which have good film formability and which can be produced by coating that use organic photoconductive materials (charge generation materials and charge transport materials) have recently been widely used.
Advantages of organic photosensitive members include very high productivity and low-cost production as well as free control of sensitivity and the like according to the selection of the photoconductive material used, so the organic photosensitive members have been extensively studied.
In addition, to improve the sensitivity and durability of electrophotographic photosensitive members, organic photosensitive members have more recently developed that have a laminated (functionally separated) photosensitive layer comprising a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material that are laminated together.
Among various charge generation materials, azo pigments have excellent photoconductivity and allow for easy production of compounds having various properties by a combination of an amine component (central skeleton) and a coupler component, so many compounds have been disclosed (Japanese Patent Application Laid-Open No. H09-048757 and Japanese Patent Application Laid-Open No. H08-087124).
However, electrophotographic photosensitive members containing these azo pigments only in the charge generation layer do not necessarily have performance that can sufficiently deal with potential variation. Moreover, with the recent tendency toward higher speed, higher image quality, and full coloring, electrophotographic photosensitive members have been more seriously requested to deal with potential variation. Especially, the initial (up to 1,000 rotations) potential variation (increase in light-area potential) and the long-term (up to 50,000 rotations) potential variation (increase in light-area potential) in a low-humidity environment are expected to be prevented.